I am developing a game for Unity 4 and would like to add GameCircle achievements to it. However, the latest GameCircle Unity plugin (found here https://developer.amazon.com/public/resources/development-tools/sdk) does not appear to work with Unity 4. The example scene and prefab files aren't opening correctly in the latest version, Unity 4.7.2. Is there a way to get a previous version of the plugin which does? Migrating to Unity 5 is out of the question for us at the moment.